The present invention generally relates to a method and arrangement for manual stop-down mirror-up operation in a single lens reflex camera.
In view of practical considerations, single lens reflex cameras are currently provided with an automatic diaphragm arrangement and a quick-return arrangement for purposes of viewing the effect of diaphragm operation within the viewfinder. In order to stop down the normally fully open diaphragm within the lens arrangement before the photographing operation, the lens barrel or the camera main body is provided with a manually operating member. By manually operating this member, the diaphragm within the lens arrangement is individually stopped down. In cases in which mirror shocks should be avoided to as great an extent possible, such as microscopic photography, copying photography, and similar camera applications, or in cases in which no long mechanical back can be obtained in the design such as in the use of super wide angle lenses or the like, the camera main body is provided with a manually operating member for purposes of swinging the mirror from the viewing position to the shutter operation position.
In cameras having split-exposure shutters such as focal plane shutters, if the shutter is caused to run before completion of lens stop-down operation, it is possible that an undesirable unevenness of the picture will result. At the time of mirror-up, the mirror has already swung to the shutter operation position, and the automatic diaphragm arrangement and the shutter device disengaging arrangement tend to operate too early and without allowing sufficient time for moving the mirror. Thus, in order to avoid an unevenness of picture, it is desirable to arrange for the diaphragm operating member to be at a stop-down position at the time of mirror-up.
In resolution of the foregoing problems, the present invention provides mirror-up and manual stop-down operations through depression of a single button. The advantages of the method and arrangement for manual stop-down, mirror-up of a single lens reflex camera according to the present invention are that the operation for mirror-up is simple, only a single member is added to the outer camera appearance, comparatively few components are required, and the components require a comparatively small space.